Mercury is a deleterious anthropogenic pollutant. Mercury is a heavy, silvery, odorless liquid that may be released into the atmosphere in a number of ways, including but not limited to, the burning of fossil fuels. In 1999, the Environmental Protection Agency (“EPA”) estimated that a year's worth of coal (in the US) contains approximately 75 tons of mercury, and the burning of this coal will lead to about 50 tons of mercury being released into our atmosphere. As part of this release mercury settles in the aquatic biosphere rendering fish potentially poisonous with recommended exposure limits. Additionally, mercury has been incorporated into everyday items, such as long-tube fluorescent light bulbs, which contain on average from 10 to 20 mg of mercury that affects the environment if not disposed of properly.
Adding to mercury's toxicity is the fact that at normal temperatures, mercury can evaporate into the air. Furthermore, when it is heated, this evaporation occurs at an elevated rate. Mercury vapor is extremely toxic to inhale, but difficult to detect due to its colorless and odorless nature. An acute exposure to mercury vapor inhaled into the lung results in a variety of lung and neurological problems including: headaches, cough, chest pain, and difficulty breathing. Continued exposure will eventually lead to loss of teeth, nausea, diarrhea and permanent lung scarring. Further, this exposure can cause severe kidney damage. Long-term exposure to mercury may cause shaking of the hands and facial muscles. However, the most deleterious neurological effects may be: headaches, trouble sleeping, personality change, memory loss, irritability, indecisiveness and loss of intelligence. Many of these symptoms can be attenuated or eliminated by avoiding further exposure, but first personnel must be able to detect mercury vapor in such areas. The termination of exposure is cogent because continual chronic exposure results in permanent injury. Consequently, mercury vapor is of major concern in the work environment, yet real-time detection and measurement of ambient mercury vapor remains costly and limited to bulky devices unsuitable to be worn in the breathing zone of workers.
In part, as a result of this heightened understanding of the consequences to humans and the environment posed by mercury and the costs associated with reducing and monitoring the release of mercury, in 1990 the Clean Air Act was amended, and the EPA was given authority to regulate mercury emissions. In recent years, the EPA has reduced the permitted concentration levels of mercury to trace levels (e.g. pursuant to the EPA the permitted concentration of mercury in drinking water is 0.002 part per million) to protect against these adverse health effects. Due to the EPA's regulations there is a need to measure the concentrations of various metal species, and this need is exacerbated by the lack of technologies to measure the presence of metals in the ultra-low (trace) concentration range. Currently only Atomic Absorbance, Atomic Emission, and Atomic Fluorescence Spectroscopies and their variants, and gold electrode conductivity meters are suitable for measurement, but such techniques require expensive and bulky equipment unsuitable for direct read operation in the breathing zone. For these reasons there is a need for a portable and comparatively inexpensive instrument, which allows for multiple approaches to detection and quantification of trace elements.